RIVER

[[File:River Thames - Isle of Dogs to Thurrock.jpg|thumb|300px|The River [[Thames]] in London, England. People have lived along the banks of this river for thousands of years.]]

A '''river''' is a [[stream]] of [[water]] that flows through a channel (or passage) in the surface of the ground. The passage where the river flows is called the river bed and the earth on each side is called a river bank. A river begins on high ground or in hills or mountains and flows down from the high ground to the lower ground, because of [[gravity]]. A river begins as a small stream, and gets bigger the farther it flows.

The water in a river is called [[fresh water]]. It comes from rain or snow and it can usually be drunk safely, unless it has been [[pollution|polluted]]. The water in a [[sea]] cannot be drunk safely because it is [[salt water]]. Both people and animals often live near rivers. They need water to survive and, for humans, rivers were once the only means of fast [[transport]].

== About rivers ==
=== The beginning of a river ===
The start of a river is called the ''source'' or ''head water''. The part of the river that is near the source is called a 'young' river. A young river is often in a V-shaped river bed, and flows quickly downhill over stones, and around big rocks. Young rivers often have lots of small [[waterfall]]s and [[rapids]].

* The source of a river may be a [[spring (water)|spring]], often on a [[hill]], [[mountain]], glacier, or another high place. A spring is water that flows out from under the ground.
* The source of a river may be a lake where lots of water from small streams gathers when it rains or snows.
* A river may begin in mountains where there is snow. The melting snow runs together to form a small stream that runs down the mountain. As more little streams run in, the main stream gets bigger, until it forms a river.
* Some rivers flow from hills where there is no snow, but lots of rain.
* Some rivers only flow after there has been rain near the head water.


=== The middle part of a river ===
The middle part of a river is called a mature river. A mature river makes a riverbed that is U-shaped. It might be very deep and run fast. It sweeps over small rocks and boulders, and makes big turns around hills and mountains. It is much wider than a young river, but not as wide as an old river. To cross over a mature river, people use bridges. Many cities and towns are built on the banks of mature rivers. Many farms that keep animals such as [[cattle|dairy cows]], [[horse]]s and [[sheep]] are along mature rivers because the animals can drink from the river every day.


=== The last part of a river ===
A river usually ends by flowing into an [[ocean]], a [[lake]] or a bigger river. The place where the river flows out into a bigger body of water is called the 'mouth' of the river.

As a river flows towards its mouth, the countryside around the river often changes from hilly to flat. As it flows over the flat land the river becomes wider and slower. A wide slow river is called an 'old river'. An old river often floods across the land after there is lots of rain at the headwaters. An old river slowly builds up its banks on either side; the high banks are called [[levee]]s. An old river often [[meanders]] (twists and turns), and sometimes, after a flood, it leaves lakes behind which are called ox-bows or [[Billabong (lake)|billabongs]]. Old rivers are the most useful type of river for growing [[crop]]s. [[Corn]], [[rice]], [[fruit]], [[cotton]], [[hay]], [[tobacco]] and [[sugar]] are some of the crops that are grown near old rivers.

The shape of the mouth depends on the conditions of the sea where it flows. If there is a strong [[tide]] where the river meets the sea, the river forms an [[estuary]]. An estuary is a wide, funnel-like mouth of the river. The fresh water of the river mixes slowly with the salt water, becoming [[brackish]] water – somewhat salty water. Many kinds of [[fish]], [[clam]]s, [[mollusc]]s and other sealife live at estuaries. Many of the world's largest [[city|cities]] and [[harbour]]s are at estuaries.

Where a river flows out to the sea, it sometimes flows very slowly through sandy or muddy land, making lots of little islands as it flows. The main stream of the river gets broken into many parts that spread out into a triangle shape like the Greek letter [[delta]]. When this happens, it is called the [[river delta|delta]] of the river. Deltas are often places that are not good for towns or farms but are very good for birds and other wildlife and [[fishing]]. Deltas are often made into [[wildlife reserve]]s. Not all rivers have deltas. There are famous deltas on the [[Nile River]], the [[Amazon River]], the [[Mekong River]], the [[Mississippi River]] and the [[Danube River]].



=== Underground rivers ===
Some rivers flow underground through [[cave]]s. Underground rivers form in places where there are lots of cracks in the rocks above, so that in rainy weather, the water runs downs and collects in small underground streams. Sometimes the underground water trickles or gushes out of the ground to form a small [[spring (water)|spring]] of water. In other places, where there are caves, the small underground streams run together to form a river. The river can sometimes run through deep wide underground caverns. While many underground rivers flow gently, some underground rivers flow fast and have [[rapids]], particularly after heavy rain. Many underground rivers flow out through a cave mouth to become an ordinary river.



== Using rivers ==
The water in rivers is "fresh water" that has come from rain, snow and from underground streams. It can usually be drunk safely by people unless it is too dirty because of mud or human [[pollution]]. People and animals need fresh water to drink, so they often live by the side of a river.

* Rivers give water for drinking, bathing and washing clothes.
* Rivers give water for [[cattle]] and other animals to drink and for people to grow plants.
* Rivers give [[Product (consumer goods)|products]] that are useful to people such as fish for food, [[clay]] for bricks and [[Reed (plant)|reeds]] to make the roofs of houses.
* Rivers can be used for transporting people, crops and other goods by boat.
* Rivers can be used to give power to turn machinery such as water [[watermill|mills]].
* Rivers give water for factories that make cloth, steel and many other products.
* Rivers sometimes have dams to hold the water for people to drink, or to make electricity.
* Rivers can be used for [[leisure]] and [[sport]]s such as swimming, boating, fishing and just walking by the river.
* Rivers often have beautiful scenery. Many painters, story-tellers and poets have painted or written about rivers.
* Rivers are sometimes turned into canals.
=== Water for living ===


=== Water for industry ===


=== Water for fun ===


== Rivers in art, literature and music ==
* [[Mark Twain]], ''The Adventures of Tom Sawyer'', (novel)
* [[Kenneth Grahame]], ''The Wind in the Willows'', (novel)

=== Rivers in photography ===


== Important rivers ==

* the [[Amazon River]] in [[South America]] is a very wide tropical river flowing through the Amazon [[Jungle]] and into the [[Atlantic Ocean]] through a large delta. Many types of fish live in it. It is the largest river in the world.
* the [[Nile River]] in [[Africa]]. For thousands of years this river has provided the people of [[Egypt]] with water to help their food grow. [[Cairo]], the biggest [[city]] in [[Egypt]] and [[Africa]], is built near the Nile's [[river delta|delta]] on the [[Mediterranean Sea]]. It is the longest river in the world.
* the [[Mississippi River]] in the [[United States]]. Many crops are grown along the sides of the Mississippi. It was also used for transport. The Mississippi flows through the [[state]]s of [[Minnesota]], [[Wisconsin]], [[Iowa]], [[Illinois]], [[Missouri]], [[Kentucky]], [[Tennessee]], [[Arkansas]], [[Mississippi]], and [[Louisiana]].
* the [[Yangtze River]], a very large river in China, the third longest in the world, and the longest in Asia
* the [[Rhine River]]
* the Rivers [[Tigris]] and [[Euphrates]]
* the [[Ganges River]]
* the [[Mekong River]]
* the [[Danube|River Danube]]
* the [[Volga River]]
* the [[St. Lawrence River]]
* the [[Murray River]] in [[Australia]], 1609 miles in length.
* the [[Congo River]]
* the [[Niger River]]
* the [[River Thames]]
* the [[Tiber River]]

=== River Terminology ===
*A '''meander''' is a bend or curve in a river.
*The '''mouth''' of a river is where the river enters the sea, ocean or lake.
*An '''oxbow''' lake is located at the side of a river and is curved like a "meander"
*A [[braided river]] is a usually slow-moving river which splits up and joins together repeatedly.

== Other types of rivers ==
* A '''submarine river''' is a stream of water that flows along under the surface of an [[ocean]]. One of them, named the [[Cromwell current]], was found in [[1952]]. ("Sub marine" comes from [[Latin language|Latin]] and means "under sea".)
* A '''subterranean river''' is a river which flows under the surface of the [[earth]]. One of them was found in [[August]] [[1958]] under the [[Nile River]]. (The term "sub terranean" also comes from Latin and means "under ground".)

==Related pages==
* [[Water]]
* [[Valley]]
* [[Lake]]
* [[Flood]]
* [[Drought]]
* [[Erosion]]

== References ==
{{reflist}} [[Category:Basic English 850 words]]
[[Category:Rivers| ]]
[[Category:Biomes]]